Ok, it’s probably not the yolk then and it’s just the fluid inside the egg and the membrane. In cases like that it can dry like glue. The most important thing is to make sure that the eyes, the nostril holes, and the vent hole are cleared from the sticky stuff. The chicks need to breath and be able to go to the bathroom and sometimes those areas can get glued over. Use a warm, damp q-tip to make sure those areas are clear. Otherwise it won’t really hurt the chick if his body fluff is hard and stiff from that stuff. If that happens to me I usually wait until the chick is a little stronger and then give a warm bath and blow dry. You can even just take a dry towel and try to rub it over the chick to get some of that stuff off.